Here's a link to the best YouTube video I can find highlighting the "incident."
http://www.youtube.com/watch?v=zcN2HrkrnF4 (pardon the German)
From this, I'm seeing two distinct events that determine the outcome of the wait/no wait debate.
1. Andy is attacking, Vino responds first, Contador starts givin'er - AC is not looking anywhere near AS when he goes past.
2. Andy looks to be shifting in the sequence leading up to the chain drop. Watch his right hand, he's riding SRAM so it's a very short action behind the brake lever but you can see the little wrist flicks that shifting SRAM creates. Does it happen a split second before the chain drops? Maybe not, but certainly in the seconds immediately prior to the chain drop. Almost immediately he tries to pick the chain back up with his left hand/front derailleur.
From the side view when his wheel bounces it looks to me like his chain gets sucked up into the chainstay. More likely though, that bounce was caused by him standing up and hammering while dropping the chain.
Ultimately this debate comes down to whether or not you believe what happened today was a the result of a "mechanical" or rider error. I completely support the gentleman's code in the TdF that you don't attack/win against a true contender when the contender is dealing with a bike issue/crash caused through no fault of his own. That's the honor in the sport (all drugs aside).
I don't see today's events unfolding as a result of mechanical. Andy shifted at the wrong time into the wrong gear or attacked in the wrong place or whatever combination was required to drop his chain. He was slow to put it back on. This happens in bike racing.
This situation is not too unlike when Lance popped out of his pedal twice in a short sequence in a previous tour on a similar climb. IIRC, Lance stated at the end of the stage his pedal was indeed broken. No one stopped for him then. They didn't even slow down. He just got up with the fire in his belly and rode himself back into the pack. The difference is he could. Apparently AS couldn't today.
I'm no fan of AC. I've been cheering for AS this whole tour. But IMO, AS's attitude/comments at the finish was as classless as AC's celebrating the move into the GC lead under unfortunate circumstances.
But it sure makes the next few stages more interesting doesn't it?